Under federal law, states can choose whether to follow the national rules or the California standards, which generally are stricter and so are better for air quality. The AQCC action thus will help preserve the economic and environmental benefits of clean car standards in Colorado, in light of the Trump Administration’s proposed rollback of the federal standards.

The LEV standards require automakers to improve the fuel efficiency of their vehicles, reaching an average fuel economy of 54.5 miles per gallon by 2025, which is almost twice what it is today. This summer, Governor John Hickenlooper issued an executive order directing Colorado to join 13 other states in the adoption of California’s LEV standards, but formal adoption of the rules required final approval by the AQCC.

“LEV standards will save Coloradans thousands of dollars in fuel costs and, on average, $2,800 over the lifetime of a new car,” Frommer said after the decision. “These standards will also result in significant GHG emissions reductions from transportation – about equal to the combined emissions of the two, coal-fired units that are scheduled for closure at the Comanche power plant in Pueblo.”

The AQCC also will establish a separate rulemaking for Zero-Emission Vehicle (ZEV) standards, which will be presented in December 2018 and considered in March 2019.